docs(coding-agent): fix invalid notify type in extensions example

The notify() API only accepts "info" | "warning" | "error" — "success"
was a copy-paste error in the example.

Co-Authored-By: julien-agent <Agents+cyolo@huggingface.co>

packages/coding-agent/docs/extensions.md

@@ -162,7 +162,7 @@ export default function (pi: ExtensionAPI) {
   pi.on("event_name", async (event, ctx) => {
     // ctx.ui for user interaction
     const ok = await ctx.ui.confirm("Title", "Are you sure?");
-    ctx.ui.notify("Done!", "success");
+    ctx.ui.notify("Done!", "info");
     ctx.ui.setStatus("my-ext", "Processing...");  // Footer status
     ctx.ui.setWidget("my-ext", ["Line 1", "Line 2"]);  // Widget above editor (default)
   });